Collateral channels are present in arterial, venous, and lymphatic circulation throughout the body. Collateral circulation is established through connection(s) or anastomoses between two vessels supplying or draining two adjacent vascular regions. Blood supply to an organ is maintained through these collateral channels when the main vessel is obstructed. Collateral circulation, therefore, provides a compensatory mechanism that allows amelioration of the detrimental effect of blood flow cessation due to obstriction of a vascular pathway.
The areas of the body where collateral blood flow is of particular importance are that of the cerebral and coronary circulation where interruption or cessation of blood supply to the brain or the heart may be have devastating consequences, e.g., causing stroke or myocardial infarction. Collateral circulation is also present in the extremities. Occlusion of blood supply to the extremities is usually due to atherosclerosis. Clinical symptoms depend upon the extent of obstruction, the rate of progression, the vessels involved, and whether collateral flow exists.
Current treatment of vascular occlusive disease includes percutaneous transluminal angioplasty (PTCA), thromboendarterectomy, bypass graft using woven prosthetic tube or autogenous vein anastomosed end-to-side to the vessel above and below the obstruction, or resection with graft replacement. Unfortunately, one common complication is distal embolization of vascular debris, e.g., calcium, atheromatous plague, thrombi, fat, and vascular tissue, generated during the procedures. Distal embolization of debris to a coronary artery can cause further myocardial ischemia and infarction. Embolization of debris to the distal extremities may cause gangrene of the toes and foot.
New devices and methods are thus needed for patients undergoing vascular procedures for treatment of occlusive vascular disease, devices that minimize the risk of distal embolization and end organ damage.